Add UMA metric to track the time elapsed since a WebAPK was last launched

chrome/android/java/src/org/chromium/chrome/browser/webapps/WebappActivity.java

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.webapps;
 
 import android.content.Intent;
 import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.graphics.drawable.Drawable;
@@ skipping 387 matching lines @@
         // user clearing their history or not launching the web app recently.
         // Restore the data if necessary from the intent.
         storage.updateFromShortcutIntent(getIntent());
 
         // A recent last used time is the indicator that the web app is still
         // present on the home screen, and enables sources such as notifications to
         // launch web apps. Thus, we do not update the last used time when the web
         // app is not directly launched from the home screen, as this interferes
         // with the heuristic.
         if (mWebappInfo.isLaunchedFromHomescreen()) {
+            onWillUpdateLastUsedTime(storage);

[dominickn, 2017/06/08 05:15:27]

It would be good if you could add a quick test that after installing a webapp,
wasLaunched() is false, and then after launch, it's true.

[pkotwicz, 2017/06/12 20:34:46]

How do you suggest that I add such a test? I don't think that I can write the
test that you want as a JUnit test. I have already added two integration tests
as part of this CL

I could test that registering a webapp does not cause WebappDataStorage to think
that the webapp has been launched.

[dominickn, 2017/06/14 00:19:39]

Ah yes, the integration test is sufficient with another assert. Thanks

+            storage.setWasLaunched();

[dominickn, 2017/06/08 05:15:27]

I think you need to setWasLaunched() before onWillUpdateLastUsedTime()

[pkotwicz, 2017/06/12 20:34:46]

Actually, it is important for the WebApkActivity method to be run before
WebappDataStorage#setHasBeenLaunched() is called because WebApkActivity needs to
know whether the lauch is the first launch.

I have changed around the code. Hopefully, it is clearer now

             storage.updateLastUsedTime();
         }
     }
 
+    /** Called prior to updating the "last used" time in WebappDataStorage. */
+    protected void onWillUpdateLastUsedTime(WebappDataStorage storage) {}
+
     protected void initializeSplashScreenWidgets(int backgroundColor, Bitmap splashImage) {
         Bitmap displayIcon = splashImage == null ? mWebappInfo.icon() : splashImage;
         int minimiumSizeThreshold = getResources().getDimensionPixelSize(
                 R.dimen.webapp_splash_image_size_minimum);
         int bigThreshold = getResources().getDimensionPixelSize(
                 R.dimen.webapp_splash_image_size_threshold);
 
         // Inflate the correct layout for the image.
         int layoutId;
         if (displayIcon == null || displayIcon.getWidth() < minimiumSizeThreshold
@@ skipping 292 matching lines @@
         return new WebappDelegateFactory(this);
     }
 
     // We're temporarily disable CS on webapp since there are some issues. (http://crbug.com/471950)
     // TODO(changwan): re-enable it once the issues are resolved.
     @Override
     protected boolean isContextualSearchAllowed() {
         return false;
     }
 }